I had a singing gig at the Kutshers resort in the Catskills, before it closed. (This is a true story.) I was in a vocal quartet for the religious services at the Jewish High Holy Days. Two of the guys in the quartet were not Jewish. One of them asked the other what he would say if one of the congregants asked if he was Jewish. The other said, "I'll say what I always do to that question: 'Isn't everyone?'"
mrincredible